EngineerHub.orgDrawing No. EH–TH–010 // Thermal Engineering & HVAC
Dehumidifier Sizing Calculator
Reviewed August 2026
Choose a simple appliance-sizing guide or estimate the actual moisture load from humidity, air exchange and internal sources.
01 // Space & moisture
02 // Recommended capacity
Background & method
The guide mode follows the capacity ranges published by ENERGY STAR for damp, very damp and wet spaces. Psychrometric mode adds a physically based moisture balance for users who know indoor/outdoor conditions. The psychrometric calculation assumes standard atmospheric pressure of 101.325 kPa; high-altitude applications should use a pressure-adjusted model.
FAQ
Water-removal capacity falls as air temperature drops because the coil has less moisture available to condense and frosting can limit operation.
Around 45–55% RH is a common comfort and moisture-control range. Very low RH is usually unnecessary and may increase energy use.
It estimates water contained in the room air, infiltration moisture and internal moisture generation instead of relying only on floor area and dampness category.